Implementation of sliding mode control for current sharing in fixed frequency voltage regulator modules

Voltage regulator modules (VRMs) have to maintain perfect current sharing between modules in both static and dynamic loading. In this study, sliding mode control was applied to both the voltage loop and the current share loop of the two-phase VRM with the aim of providing an effective current sharing scheme. Unlike other sliding mode control implementation that uses infinite switching frequency in its control method, fixed switching frequency was used. Derivation for the fixed frequency sliding mode control was done in the analog domain and transformed into the digital domain. A simulation model using PSIM was developed for both the analog and the digital control implementations. Results show that current sharing is achieved in both the analog and the digital control.